Precautions

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly and to check for unwanted effects. Blood tests may be needed to check for unwanted effects. Your blood pressure should be checked by your doctor every 2 weeks while taking this medicine.

Using this medicine while you are pregnant can cause very serious birth defects. Use two forms of effective birth control to keep from getting pregnant while you are using this medicine and for at least 1 month after you stop taking the medicine. The most effective forms of birth control are hormone birth control pills, patches, shots, vaginal rings, or implants, or a vasectomy (for men). One of these forms of birth control should be combined with a condom, a diaphragm, or a cervical cap. If a woman has had a tubal ligation or has an IUD, she does not need to use a second form of birth control. If you think you have become pregnant while using this medicine, tell your doctor right away.

If you are a woman who can get pregnant, you must have a negative pregnancy test before you will be allowed to take this medicine. You will also be required to have a pregnancy test every month during your treatment and 1 month after stopping therapy. If you miss a period while you are using this medicine, tell your doctor right away.

Do not use this medicine together with a nitrate medicine (such as nitroglycerin) or nitric oxide donor (such as amyl nitrite). Do not use this medicine together with dipyridamole, theophylline, or medicine for impotence (such as sildenafil, tadalafil, vardenafil). Using these medicines together may cause hypotension (low blood pressure).

This medicine could lower your blood pressure and cause you to feel dizzy or lightheaded. Avoid driving, using machines, or doing anything else that could be dangerous until you know how this medicine affects you. If you feel dizzy, lie or sit down so you do not faint.

Pulmonary edema may occur with this medicine. Check with your doctor right away if you have chest pain, difficult, fast, or noisy breathing, sometimes with wheezing, blue lips and fingernails, pale skin, increased sweating, coughing that sometimes produces a pink frothy sputum, or shortness of breath.

Tell your doctor if you are smoking before taking this medicine.

Do not take other medicines unless thy have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (eg, St. John's wort) or vitamin supplements.